The embodiment of the invention relates to a light source and a backlight module with the light source.
A backlight module of a conventional liquid crystal device (LCD) is a component for providing light for display and can be widely employed in various applications such as information, communication and consumer products. Among them, light emitting diode (LCD) backlight modules draw more and more attention of manufacturers due to their advantages such as low power consumption, full color saturation, low contamination, long service life, etc. As shown in FIGS. 1A and 1B, a conventional LED backlight module comprises a bottom reflective plate 10, a light guide plate 11 converting a linear light source into a planar light source, a lower diffuse plate 12, a lower prism plate 13, an upper prism plate 14, and an upper diffuse plate 15 that are disposed sequentially on top of one another. The lower and upper diffuse plates 12 and 15 are used to diffuse the incident light. The lower and upper prism plates 13 and 14 are used to improve light intensity of the incident light. A light source 16 is disposed on both sides of the light guide plate 11. The light source 16 is enclosed by a reflective cover 17 reflecting the light from the light source 16 toward the light guide plate 11. The backlight module may further comprise other necessary components such as a support frame.
A cold cathode fluorescence lamp (CCFL) is a typical linear light source used for a LCD backlight. As shown in FIG. 2, a CCFL comprises a transparent light tube 1 with fluorescence material coated on the inner surface of the light tube 1 and a positive electrode 2 and a negative electrode 3 that are disposed on opposing ends of the light tube 1. Inert gas such as Ar and Ne gas as well as a trace amount of Hg gas is filled within the light tube 1. During operation of the CCFL, a high voltage is applied across the electrodes 2 and 3 to fire a discharging process. The Hg gas is thus excited to emit a UV light, which in turn excites the fluorescent material coated on the inner surface of the light tube 1 to emit a visible light. FIG. 3 illustrates a conventional backlight module with a light source such as a CCFL. As shown in FIG. 3, a part of the light from the light tube 1 is transmitted directly into the light guide plate 11 along a light path “a,” a part of the light is reflected into the light guide plate 11 by the cover 17 along a light path “b,” while a part of the light is reflected back into the light tube 1 by either the cover 17 or the light guide plate 11 and partially absorbed by the light tube 1. In a conventional backlight module, such absorption can cause a loss up to more than 30% of all light emitted from the light source.